Bone Instrumentation Cover or Shield

ABSTRACT

A bone instrumentation cover or shield has a hollow cap or casing for encapsulating projecting parts of instrumentation installed in a bone, and a fastener portion for securing it to the bone or to parts of the instrumentation. The instrumentation shield or cover is made of medically safe material, in various sizes, and may be a rigid casing or pliable, stretchable, or adaptable with slidable, displaceable or pleated panels to provide a medically safe physical barrier between projecting parts of bone instrumentation constructs and surrounding bone and soft tissues, in order to minimize local irritation or injury and to provide a barrier to ingrowth from bone and/or fibrous tissues. The cap or casing is readily applied over the instrumentation, then cinched, tied or fastened to the instrumentation or adjacent areas.

CROSS-REFERENCE TO RELATED APPLICATION

This United States Non-Provisional Patent Application is a ContinuationApplication of U.S. patent application Ser. 10/634,368, filed Aug. 6,2003, entitled “Bone Instrumentation Cover or Shield,” the disclosuresof which are incorporated by reference in their entirety.

FIELD OF THE INVENTION

This invention generally relates to a device used in protect the bodyand the instrumentation installed in bone during spinal orreconstructive surgery, and particularly to a bone instrumentation coveror shield.

BACKGROUND OF INVENTION

Spinal bone deterioration, disc rupture, degenerative disc disease ordeformity is surgically correctable by installing a rod secured topedicle screws mounted into good bone in order to support or reinforcethe deteriorated, weakened, or deformed area.

However, the presence of instrumentation installed in bone can presentproblems for the patient. Projecting parts of the instrumentation canirritate and cause swelling or injury to the surrounding tissues.Ingrowth of bone or fibrous tissue into parts of the instrumentation ispossible if the bone or tissue regenerates, causing possibleinterference with the function of the instrumentation or perhaps makingit difficult to later remove the instrumentation if it is no longerneeded or if a next progressive stage of instrumentation is required.Many of the systems in use tend to be fairly bulky and frequently leadto problems within patients. Bursae may form which can lead to pain andpossible skin necrosis and breakdown. Removing the instrumentation mayultimately be necessary in such cases. It is therefore desirable toprovide a way to protect the body and the instrumentation installed inbone during spinal or reconstructive surgery.

SUMMARY OF INVENTION

In accordance with the present invention, a bone instrumentation coveror shield comprises a cap or casing which is dimensioned to be placedover and to encapsulate projecting parts of instrumentation installed ina bone, and a fastener portion provided at a lower edge of the cap orcasing for securing it to the bone or to parts of the instrumentationwhere it is installed in the bone. The cap or casing is shaped anddimensioned to fit over the projecting parts of the instrumentation. Thefastener portion is designed to attach and hold the cap or casing to thebone or to parts of the instrumentation installed in the bone.

In one preferred embodiment, the cover or shield is formed with a hollowcap or casing in a suitable shape such as a three-dimensional oval orparallelpiped for fitting over the projecting parts of theinstrumentation, and has a lower frame with a toothed-edge bottom forlocking on to the parts of the instrumentation that are mounted into thebone (pedicle screws). The fastener can include pre-loaded sutures forattachment to the bone or to adjacent parts of the instrumentation.

In another preferred embodiment, the cover or shield is formed with ahollow cap or casing as described above, and a lower frame is providedwith an aperture to accommodate parts of the instrumentation that extendthere from to where they are mounted into or fastened to the bone.

In a further embodiment, the cap or casing is formed as a pliable orflexible pouch, and the fastener portion is formed by one or moredrawstrings for cinching the lower edge of the pouch opening around theparts of the instrumentation mounted into or fastened to the bone. Theextra lengths of the drawstrings may be fastened to the bone orinstrumentation like the sutures described above.

In yet another embodiment, the cap or casing is formed as a pliable orflexible sheath, and the fastener portion is formed by a lower cinchring having openings therein for threading through a number of suturestrings for tightening the cap vertically down to the cinch ring overthe instrumentation, and one or more drawstrings in the cinch ring fortightening horizontally around the instrumentation.

In still another embodiment, the cap or casing is formed with slidableor displaceable panels or with pleats, for adjustment of its length,width, or height snugly around the instrumentation.

Other objects, features, and advantages of the present invention will beexplained in the following detailed description of the invention havingreference to the appended drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic drawing of a first embodiment of the inventionhaving a cover or shield formed with a hollow cap or casing and a lowerframe with a toothed-edge bottom for locking on to instrumentationmounted into the bone.

FIG. 2 is a schematic drawing of a second embodiment in which the coveror shield is formed with a hollow cap or casing and a lower frame withan aperture for the instrumentation.

FIGS. 3A and 3B are schematic drawings of a third embodiment in whichthe cover or shield is a pliable or flexible pouch, and the fastenerportion has drawstrings for cinching around the instrumentation.

FIG. 4 is a schematic drawing of a fourth embodiment in which the coveror shield is formed with a cap, and the fastener portion is formed by alower cinch ring threaded with a number of suture strings for tighteningthe cap vertically down to the cinch ring, and drawstrings fortightening the cinch ring horizontally around the instrumentation.

FIG. 5 is a schematic drawing of a fifth embodiment in which the coveror shield has slidable or displaceable panels for adjustment of itslength, width, or height around the instrumentation.

DETAILED DESCRIPTION OF INVENTION

Referring to FIG. 1, a first embodiment of the instrumentation cover orshield in accordance with the present invention is formed with a hollowcap or casing 10 and a lower frame 10 a formed with a toothed-edgebottom for locking onto instrumentation, i.e., pedicle screws 12 havingscrew-threaded lower portions which are mounted into the bone or bonesof the patient. A rod 14 is secured through the post portions of thepedicles 12 to provide rigid instrumentation support across a given areaof the bone. When the instrumentation has been mounted into the bone ina surgical procedure, the parts projecting above the bone can causeirritation of injury to surrounding bones or tissues. The cover casing10 is designed and dimensioned to encapsulate the projecting parts toprevent irritation or injury. The cover is applied from the dorsalaspect, inserting the longitudinal rod and pedicle screw ends throughthe mid-line aperture, then using the toothed edges of the lower frame10 a to lock onto the lower parts of the pedicle screw 12 adjacent wherethey enter the bone. The toothed edge has teeth spacings for lockingonto the projecting stems of the pedicle screw. Sutures 16 may also bepre-loaded at manufacture or attached to openings around the edge of theframe 10 a to allow fastening of the cover to the adjacent bone ortissue or instrumentation construct.

The instrumentation cover is designed to cover any spinal or other boneinstrumentation installed in the body. The cover can be used for pediclescrew/rod constructs, pedicle screw/plates, bone anchors, or hook androd constructs, such as are commonly used for cervical, lumbar, orthoracic spinal instrumentation. The shield or cover is made of proven,medically safe material, such as GoreTex,™ Dacron,™ polyurethane, or anyother safe, implantable material. The cover may be intended to bepermanently installed, or may be removable in a subsequent surgicalprocedure. The shield or cover preferably is in the form of a solidrectangle or solid oval or other suitable shape and closely fits ontothe instrumentation in a manner analogous to an armrest cover on the armof a chair. It can be made in different sizes or shapes for one-level,two-level, or multi-level instrumentation, and may also be adjustable insize (see further embodiments described below). The shield or coverprevents ingrowth of bone or fibrous tissue into interstices of theinstrumentation because it provides a mechanical barrier to suchintrusion. If the cover needs to be removed, such as when theinstrumentation is to be adjusted, replaced, or removed, it is removedin a similar surgical procedure where it is accessed through an incisionand its lower frame and/or sutures or other fasteners are removed toexpose the instrumentation.

The instrumentation cover may also be made from a molded material, suchas polyurethane foam, or a moldable material such as a non-toxic putty,or from a pliable or stretchable material as long as it is safe forimplantation. The cover is designed to fit or to be adjusted around theinstrumentation so that it covers it snugly and dislodgement ordisplacement is precluded. The cover is typically installed immediatelyafter placement of the instrumentation. Permanent sutures may be used,or absorbable, biodegradable sutures may be used to initially hold thecover in place until healing of the soft tissue surrounding the cover.The instrumentation cover may also be made of a hardenable or gelablematerial such as polycarbonate urethane, elastomeric material, orpolyurethane foam, which can cure in situ and has well-establishedbiochemical compatibility with excellent mechanical strength and elasticproperties.

Another possible material for the cover is a hydrogel or “bioglue” whichis composed of bovine albumin and gluta-aldehyde. This has been used asa chemical adhesive and can be applied around the instrumentation usinga two-chambered cartridge stored at room temperature. It can be injectedinto a form placed over the instrumentation and solidified to 90% solidwithin 30 seconds, and completely in two minutes, without generation ofheat.

In FIG. 2, a second embodiment of the invention is shown in which thecover or shield is formed with a hollow cap or casing 20, similar to theone described previously, and a lower frame 20 a with an open box-likeaperture for accommodating different configurations or sizes ofinstrumentation (here again, pedicle screws 12). Sutures 26 are anchoredto small openings around the edges of the lower frame and used to holdthe cover in place by attachment to adjacent bone areas or tissue.

In FIGS. 3A and 3B, a third embodiment of the cover or shield is formedas a pliable or flexible pouch 30 with drawstrings 36 for tightening thepouch down onto the instrumentation and cinching it around the parts ofthe instrumentation (here again, pedicle screws 12) to hold it in place.The ends of the drawstrings may be wrapped around the instrumentationconstruct or tied to adjacent bone areas or tissue or instrumentationconstruct.

In FIG. 4, a fourth embodiment of the cover or shield is formed with apliable or flexible cap or sheath 40 for encapsulating theinstrumentation, and a lower cinch ring 42 for tightening the cap downaround the instrumentation. The cinch ring has openings 42 a throughwhich a number of adjustable suture strings 46 a tied to the lower edgeof the cap portion 40 are threaded. The cinch ring 42 and cap portion 40are deployed over the instrumentation, and then the loose ends of theadjustable suture strings are pulled through the cinch ring openings 42a to tighten the cap vertically down onto the instrumentation. Twosuture strings 46 b on opposite sides of the cap have ends that areattached to the cinch ring and are not adjustable, as their function isto tie the cinch ring to the cap portion so that it does not slip awayfrom the cap and adjustable sutures while being handled. The cinch ringis in tubular form and is made of a flexible material, such as asynthetic fabric, so that it can also be cinched circumferentially(horizontally) around the lower parts of the instrumentation adjacentthe bone, using drawstrings 48. The suture string and drawstring endsmay be trimmed and tied off to the cinch ring or instrumentationconstruct to prevent accidental removal.

In FIG. 5, a fifth embodiment of the cover or shield has a casing formedwith slidable or displaceable parts or panels 50, 52 for adjustment ofits length around the instrumentation (in the direction of thebidirectional arrow in the figure). Alternatively, the panels may beformed with pleated parts for making the dimensional adjustment. Thepanels may similarly be made adjustable in width or height. Sutures 56attached to the lower frame parts 50 a, 52 a are used to fasten thecover to the instrumentation and/or adjacent bone areas or tissue.

In summary, the bone instrumentation shield or cover is designed toprovide a medically safe physical barrier for implantation betweenprojecting parts of bone instrumentation constructs and surrounding boneand soft tissues. The shield or cover minimizes local irritation orinjury to soft tissues from the instrumentation and also serves as abarrier to ingrowth from bone and/or fibrous tissues. It can be formedin a variety of forms, from solid casing, to semi-pliable sheath-likestructure, to soft pouch or cinch sack. With or without cross clips inplace, the cover can be readily applied from the dorsal aspect over theinstrumentation, then cinched, tied or fastened to the instrumentationadjacent where it enters the bone or to the adjacent bone area oftissue, using suture ties, suture strings, drawstrings and the like. Thecover is made of medically safe material, and can come in various sizesor constructed to be pliable, stretchable, or adaptable with slidable,displaceable or pleated panels. A variety of dimensional arrangementsmay be made for single-level, two-level, three-level and long,multilevel instrumentation constructs.

It is understood that many modifications and variations may be devisedgiven the above description of the principles of the invention. It isintended that all such modifications and variations be considered aswithin the spirit and scope of this invention, as defined in thefollowing claims.

1-20. (canceled)
 21. A bone instrumentation cover capable of beinginstalled over bone instrumentation which projects from the bone duringbone repair or reconstruction surgical procedure on an animalcomprising: a hollow cap sized for encapsulating a part of a boneinstrumentation which has been installed in bone, the hollow cap adaptedfor placement in the body of the animal and for encapsulating a part ofthe bone instrumentation which projects from the bone, the hollow capbeing adapted to provide a medically safe physical barrier between thepart of the bone instrumentation and the surrounding bone and softtissue, the hollow cap being adapted to separate the part of the boneinstrumentation from substantially all of the surrounding soft tissue sothat the hollow cap prevents ingrowth of substantially all of thesurrounding soft tissue through the cap into the bone instrumentationwhich projects from the bone, and the hollow cap having a fastenerportion adapted for securing the cap to the bone instrumentation portionwhich projects from the bone.
 22. A bone instrumentation cover or shieldaccording to claim 21, wherein the fastener portion includes: a cinchring provided with openings therein, said cinch ring not being a part ofsaid hollow cap, and said cinch ring being tubular in form having one ormore draw strings for tightening the hollow cap circumferentially aroundthe instrumentation during said bone repair or reconstruction surgicalprocedure, and a suture string for securing the hollow cap to one ofadjacent bone and adjacent tissue.
 23. A bone instrumentation coveraccording to claim 22, further including a plurality of first suturestrings, each first suture string having a first end and a second end,the first ends of the first suture strings being fixedly connected tothe hollow cap, and the second ends of the first suture strings arethreaded through the cinch ring for tightening the hollow cap to thecinch ring with the hollow cap extending over the bone instrumentationinstalled during the bone repair or reconstruction surgical procedure.24. A bone instrumentation cover according to claim 23, furtherincluding a second suture string with a first end of the second suturestring coupled to an edge of the cap and with a second end of the secondsuture string coupled to the cinch ring.
 25. A bone instrumentationcover according to claim 24, further including an additional secondsuture string with a first end of the additional second suture stringcoupled to an edge of the cap and with a second end of the additionalsecond suture string attached to the cinch ring and wherein the secondsuture string and additional second suture string are on opposite sidesof the hollow cap.
 26. A bone instrumentation cover according to claim25, wherein the hollow cap is adapted for removal in a subsequentsurgical procedure.
 27. A bone instrumentation cover according to claim21, wherein the hollow cap encapsulates substantially all of the boneinstrumentation which projects from the bone.
 28. A bone instrumentationcover capable of being installed in vivo over the bone instrumentationduring bone repair or reconstruction surgical procedure, comprising: ahollow cap shaped to encapsulate a part of a pedicle screw which hasbeen installed in bone in the body of a human, the hollow cap beingshaped to encapsulate a part of the pedicle screw which projects fromthe bone and is in the body of the human, the hollow cap being adaptedfor placement in the body of the human, the hollow cap being adapted toseparate the part of the pedicle screw in the body of the human fromsurrounding bone and soft tissue, the hollow cap separating the part ofthe pedicle screw from substantially all of the surrounding soft tissueso that the hollow cap prevents ingrowth of bone or tissue through thecap into the part of the pedicle screw which projects from the bone, anda fastener for snugly securing the cap to the pedicle screw.
 29. A boneinstrumentation cover according to claim 28, further including suturesthat are absorbable in vivo for securing the hollow cap to one ofadjacent bone and adjacent tissue.
 30. A bone instrumentation coveraccording to claim 29, wherein the sutures include a plurality ofadjustable suture strings, each adjustable suture string having a firstend and a second end, the first ends of the adjustable suture stringsbeing fixedly connected to the hollow cap, and the second ends of theadjustable suture strings are threaded through a cinch ring tighteningthe hollow cap to the cinch ring with the hollow cap extending over thepedicle screw installed during the bone repair or reconstructionsurgical procedure.
 31. A bone instrumentation cover according to claim30, further including a non-adjustable suture string with a first end ofthe non-adjustable suture string tied to a lower edge of the cap andwith a second end of the non-adjustable suture string attached to thecinch ring.
 32. A bone instrumentation cover according to claim 30,wherein the cinch ring has openings therein, said cinch ring not being apart of said hollow cap, and said cinch ring being a tubular form.
 33. Abone instrumentation cover according to claim 21, wherein the hollow capincludes pleats adapted for adjustment of one of the length, width andheight of the hollow cap so that the hollow cap fits snugly around thebone instrumentation.
 34. A bone instrumentation cover or shield capableof being installed over the instrumentation during bone repair orreconstruction surgical procedure comprising: a cap comprising meansadapted for placement in the body of the animal and for separating aprojecting portion of bone instrumentation which has been installed inbone in vivo in the animal from substantially all of the surroundingsoft tissue and for providing a medically safe physical barrier betweenthe part of the bone instrumentation which projects from the bone andthe surrounding soft tissue in the animal so that the cap preventsingrowth of substantially all of the surrounding soft tissue into thebone instrumentation which projects from the bone.
 35. A boneinstrumentation cover according to claim 21, wherein the fastenerportion includes a lower frame of the hollow cap provided with an open,box-like aperture shaped for locking the cap to the boneinstrumentation.
 36. A bone instrumentation cover according to claim 21,wherein the hollow cap is made of a medically safe material consistingof GoreTex™ or Dacron™ or polyurethane.
 37. A bone instrumentation coveraccording to claim 28, wherein the hollow cap is made of a medicallysafe material consisting of GoreTex™ or Dacron™ or polyurethane.
 38. Thecombination of a bone implant and a barrier comprising: a bone implantcapable of extending from the bone of an animal, and a barrier materialadapted for snugly covering only the portion of the bone implant in theanimal which projects from the bone and separating the bone implant fromsubstantially all of the surrounding soft tissue, wherein the barriermaterial is a medically safe physical barrier between the portion of thepart of the bone implant that is covered and the surrounding soft tissueof the animal and wherein the barrier material prevents ingrowth ofsubstantially all of the surrounding tissue into the instrumentation.39. The combination of claim 38, wherein the bone implant is a pediclescrew.
 40. The combination of claim 38, wherein the barrier material isdesigned to be adjusted around the portion of the bone implant whichprojects from the bone so that it snugly covers the portion of the boneimplant which projects from the bone.
 41. The combination of claim 38,wherein the barrier material is hydrogel.
 42. The combination of claim34, wherein the means for providing a medically safe physical barriercomprises hydrogel.
 43. The combination of claim 21, wherein the hollowcap comprises hydrogel.